The present invention relates generally to a circuit board packaging process, and more particularly to a circuit board packaging process for obstructing the electromagnetic interference.
The conventional process for packaging a circuit board involves a first step in which the circuit board with electronic parts being mounted thereon is placed on a die casting machine. As the upper mold and the lower mold are closed, the molten resin is forced into the mold. Upon completion of the hardening of resin, the finished product is removed from the mold.
The above packaging process is carried out in such a manner that the circuit carries out the signal transmission via the resin layer. Under such a circumstance, it is devoid of the protection of the metal layer. As a result, the system operation is susceptible to electromagnetic interference, thereby resulting in the signal instability. In order to provide a remedy, the circuit board is manually packaged in a metal shell 12, and then an insulation substrate 14 is sputtered, as shown in FIG. 1. This technique involves the use of an inert gas, such as argon ion, which is accelerated in the vacuum to smash the target. As a result of the smash sputtering, the surface of the substrate 14 is provided with a passivation film 16 to prevent the electromagnetic interference. Alternatively, the inner side of the substrate 14 is provided with a copper piece 18 to prevent the electromagnetic interference, as shown in FIG. 2.
The passivation film or the copper piece is provided after the packaging process is completed. In light of the passivation film or the copper piece not being formed integrally, it is apt to deviate to impair the prevention of the electromagnetic interference. In addition, the manual operation is time-consuming. The copper piece is joined with the substrate by drilling or bending, thereby resulting in an increase in production cost.
The primary objective of the present invention is to provide a circuit board packaging process for enhancing the efficiency of preventing the electromagnetic interference.
It is another objective of the present invention to provide a cost-effective process for packaging a circuit board to prevent the electromagnetic interference.
The process of the present invention involves a first step in which a circuit board is welded with a predetermined number of pins and is then arranged in the lower mold of a first molding tool. The upper mold of the first molding tool is joined with the lower mold before the resin is injected. The mold is then opened to remove therefrom a semifinished product, which is then provided with a metal passivation layer and is subsequently placed in a second molding tool to carry out another packaging operation. The second molding tool is finally opened to remove therefrom a finished product.